Metal-organic framework derived vanadium-doped TiO2@carbon nanotablets for high-performance sodium storage

Tianhao Yao; Hongkang Wang

doi:10.1016/j.jcis.2021.06.143

Metal-organic framework derived vanadium-doped TiO₂@carbon nanotablets for high-performance sodium storage

J Colloid Interface Sci. 2021 Dec 15:604:188-197. doi: 10.1016/j.jcis.2021.06.143. Epub 2021 Jun 29.

Authors

Tianhao Yao¹, Hongkang Wang²

Affiliations

¹ State Key Lab of Electrical Insulation and Power Equipment, Center of Nanomaterials for Renewable Energy (CNRE), School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, PR China.
² State Key Lab of Electrical Insulation and Power Equipment, Center of Nanomaterials for Renewable Energy (CNRE), School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049, PR China. Electronic address: hongkang.wang@mail.xjtu.edu.cn.

PMID: 34265679
DOI: 10.1016/j.jcis.2021.06.143

Abstract

Titanium dioxide (TiO₂) as a potential anode material for sodium-ion batteries (SIBs) suffers from the intrinsic poor electronic conductivity and sluggish ionic diffusivity, thus usually leading to the inferior electrochemical performance. Herein, we demonstrate a facile strategy to enhance the sodium storage performance of TiO₂via vanadium (V) doping, using the pre-synthesized V-doped Ti-based metal-organic framework (MOF, MIL-125) as the precursor, which can be converted into the V-doped TiO₂ with simultaneous carbon hybridization and controlled V-doping amount (denote as V_xTiO₂@C, where × represents the V/Ti molar ratio (R_V/Ti)). V-doping not only affects the morphology of the MIL-125 changing from thick to thin nanotablets, but also greatly enhances the electrochemical performance of the V_xTiO₂@C. When used as an anode for SIBs, the V_0.1TiO₂@C exhibits a much higher reversible capacity of 211 mAh/g than that for the undoped TiO₂@C (only 156 mAh/g) after 150 cycles at 100 mA/g. Even after high-rate long-term cycling, the V_0.1TiO₂@C can still display a capacity of 180 mAh/g with a high capacity retention of 137% at 1000 mA/g after 4500 cycles. Structural/electrochemical measurements reveal that V-doping induces the formation of oxygen vacancies as well as Ti³⁺ species, which efficiently improve the electric conductivity and the ion diffusivity of the electrode. Meanwhile, the thinner V_0.1TiO₂@C nanotablets with porous structure and carbon hybridization could facilitate the ion/electron transfer with shortened diffusion pathways.

Keywords: Electrochemical properties; Metal–organic framework; Sodium-ion batteries; Vanadium doping; titanium dioxide (TiO(2)).